Aircraft/aerospace, automotive, and oil/gas structural members are highly stressed components, made of expensive high strength and moderate toughness stainless steels that are used in aggressive corrosive environments. Their high costs are due to large amounts of alloying elements and expensive processing. The availability of some of the alloying elements, by way of example, cobalt (Co) is limited and their use poses future economic and military risks.
The performance of an aircraft/aerospace, etc. stainless steel at room temperature consists of an ultimate tensile strength of 250 to 280 ksi, a yield strength of 200 to 240 ksi, and resistance to corrosion in aggressive environments. As used herein the term “high strength stainless steel” means a high strength steel that has this performance.
Recently introduced Ferrium S53 is exemplary of an expensive high-strength, moderate impact toughness, quench and tempered martensitic, secondary-hardened stainless steel that is used for structural aerospace components. Its high cost is due to 14% by weight of cobalt (Co), 2% by weight of molybdenum (Mo), and 5.5% by weight of nickel (Ni) and has limited the use of this steel.
Carpenter Custom 465 is another example of an expensive high strength stainless steel with 11% by weight of nickel (Ni) and 1% by weight of molybdenum (Mo). It is a moderate impact toughness martensitic age-hardening (maraging) stainless steel that is used for structural aerospace, military, and oil/gas drilling applications.
Ferrium S53 and Carpenter Custom 465 share the cost shortcomings of costly raw materials and the high energy consuming processes of vacuum arc remelting (VAR) and electroslag remelting (ESR).